Confirming this

Confirming this

Happens for me too. Exact steps to reproduce:

- Make a sheet with a list in it. (I have one with a fixed-height list as a docked item, in case this makes a difference.)
- Drag as if to scroll the list, and release in the region above the list but not outside the sheet/in the mask.
- Click the mask; the sheet disappears but the mask stays, and the application becomes unusable.